It was almost 10 years ago that Barbara Ehrenreich, newly diagnosed with breast cancer, discovered a subject that really made her mad: positive thinking.

"When I reached out, all I could find were these exhortations to be positive or cheerful because it will make you better," she said. "It was either smile or die."

She refused to do either, preferring instead to explore what she considers an epidemic of forced cheerfulness. Her just-published book, "Bright-Sided: How the Relentless Promotion of Positive Thinking Has Undermined America," is a provocative look at the happiness industry, which she believes is partly responsible for some big bummers, everything from our slide into war to the economic crisis.

Ehrenreich, an activist and writer based in Alexandria, Va., is best known for her work on poverty and the false promises of the American dream, subjects of her bestselling books "Nickel and Dimed" and "Bait and Switch." But in both books, she said, there was the lurking presence of mandatory optimism.

The poor are always told to improve their attitude, she said. While researching "Bait and Switch," she heard laid-off workers advised to be upbeat and positive. Forget blaming fate or the economy and just charge into the next job interview with a smile.

That's when she realized, she said, that positive thinking was more widespread than she'd imagined. It was not only touted as a force against breast cancer, along with cheerful pink ribbons and stuffed bears, it was fundamental in our self-image and national character.

Positive thinking was so pervasive, she said, she found the research lonely at first. "I have never been afraid to go against conventional wisdom, but there didn't seem to be anybody on my side," she said. "When I found a couple of people, it was wonderful. We'd exchange things and share our work. We called ourselves - one of the researchers came up with this - the negateers."

Not that she's a born pessimist. Two years ago, she wrote "Dancing in the Streets, A History of Collective Joy," a book about festival traditions. But Ehrenreich describes herself as a realist, an outlook that comes partly from her scientific training - she has a doctorate in cell biology.

So how did we become so relentlessly positive? She traces the roots to Calvinism brought by white settlers to New England, followed by philosophers who urged reimagining the human condition and rejecting punitive religion. Christian Science advanced the notion that attitude heals. Fast forward to Norman Vincent Peale's "The Power of Positive Thinking," televangelists preaching a new positive theology and a new academic discipline of positive psychology, which spawned a motivational industry. Together, she says, they send the message that optimism and vigilant control over negativity lead to prosperity and well-being.

There are Happiness Makeovers and an American Happiness Association. The first conference on Happiness and Its Causes convened last year in San Francisco. Collectively, Ehrenreich said, we were so blindsided - or bright-sided - by optimistic thinking that we believed our optimistic president, that Iraq was a threat and we could win an easy war. We didn't see the economic crisis coming and made reckless investments because we thought our economy would prevail, she said.

Role of greed

What about the role of greed?

"I don't rule that out," she said, "but there was a refusal on the part of so many people that bad things can happen. ... No one could raise a hand and say, 'Excuse me, this looks really shaky.' People were fired for saying their bank's subprime exposure could be too high."

Ehrenreich is particularly troubled by the connection between optimistic thinking and health, with little hard science as evidence.

Dacher Keltner, co-director of UC Berkeley's Greater Good Science Center, dedicated to the study of positive emotions, said he expected the book - which he had not yet read - to be a much-needed review of positive psychology.

"I think this is a necessary critique of a movement that we need to take stock of," said Keltner, whose research focuses on emotion and social interaction.

'Compassion switch'

Keltner said he differentiates between two strains of positive psychology. "My take is that there is an East Coast version, which is pull yourself up by your bootstraps and be optimistic, you'll beat cancer," he said. "The Berkeley version is more, 'Let's turn on the compassion switch and make people think about others and how to cultivate empathy.' "

Ehrenreich said research into positive emotion is valuable. Relentless positive thinking, however, is something from which we must be weaned.

"We're in recovery here," she said. "The alternative is not despair, not depression. The alternative is to look at things as they are. ... Let's look at what's actually going on and see what we can do about things that are making people miserable."